Some mobile phones and information terminal devices in widespread use today include a fixed-side case having an operation section such as keys and a movable-side case having a display section such as a display panel. The movable-side case is movably connected to the fixed-side case with a connection mechanism. For example, in a slide-type mobile phone, the movable-side case can be slid relative to the fixed-side case, so that the state of the mobile phone can be changed between a closed state in which the cases overlap each other and an open state in which the cases partially overlap each other.
In this type of information terminal device, there is a gap between the movable-side case and the fixed-side case so that the movable-side case can be smoothly moved relative to the fixed-side case. Therefore, the information terminal device has a problem in that there may be an excessive play between the cases when an external force is applied to the information terminal device in the closed state. In particular, there may be an excessive play between the cases in lateral directions when an external force is applied to the cases from a side of the cases.
In an information terminal device recently proposed, an edge portion is formed around an operation section on the fixed-side case so as to be protruded toward the movable-side case, and a protruding portion is formed on a surface of the movable-side case facing the fixed-side case so as to protrude toward the fixed-side case. When an external force is applied from a side of the information terminal device in the closed state, a side surface of the protruding portion of the movable-side case is pressed against a side surface of the edge portion of the fixed-side case so that excessive play between the cases in lateral directions can be suppressed.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2008-103989
However, the existing information terminal device has a problem in that, in reality, excessive play between the cases in lateral directions is not sufficiently suppressed. That is, because both the fixed-side case and the movable-side case are made of a resin or the like having a surface hardness that is comparatively high, the edge portion of the fixed-side case and the protruding portion of the movable-side case may suffer from abrasion when the edge portion and the protruding portion repeatedly contact each other, which may lead to excessive play between the cases.
Moreover, when the cases are made of a resin or the like having a high surface hardness, shock resistance of the cases is low. Therefore, if a side surface of the edge portion is strongly pressed against a side surface of the protruding portion of the movable-side case when, for example, the information terminal device is dropped, the edge portion of the fixed-side case and the protruding portion of the movable-side case may be broken, which may lead to excessive play between the cases in lateral directions.